Method for producing a lightweight component, and support element

ABSTRACT

A lightweight component is equipped with two cover layers, which are made of a wood material, and a filling disposed in between the layers after cutting everything to size, having an edge support including thermoplastic material. The edge support is anchored in both the first and second cover layers starting from the narrow side. Anchoring is achieved by bringing the edge support into contact with the respective cover layer and coupling mechanical vibrations into the edge support by a sonotrode engaging from the narrow side. The edge support at the same time is pressed against the cover layer such that, in the region of a transition between the thermoplastic material and the wood material of the cover layer, part of the thermoplastic material is liquefied and pushed into the cover layer material, thereby producing a positively engaged anchoring after hardening.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to lightweight building boards, as used inlightweight construction and the furniture industry.

Such lightweight building boards consist of two outer, relatively thincover layers, for example particleboards, and a filling, for example ahoneycomb structure made of card, arranged between the cover layers.Lightweight building boards of this type are mechanically very stable,lightweight, and can look attractive if the edges are finished neatly.Specifically because of their low weight and also because of the lowconsumption of resources in their production, they are becomingincreasingly popular.

Edges (decorative edges) for such lightweight building boards are, forexample, plastic strips sealed on the outer surface and provided with asuitable decoration, and may furthermore be provided with an adhesive onthe rear side. Decorative edges formed as veneer edges are alsoavailable.

However, finishing the edges in such a way as to obtain an attractiveappearance has, to some extent, not yet been satisfactorilyaccomplished. In particular, for the production of ready-made andmass-produced products, it would be desirable if a cut-to-sizelightweight building board could be provided with an edge by a craftsmanafter the cutting-to-size operation, without involving great effort andusing available tools.

For the secure fastening of the edge, the prior art discloses on the onehand the provision of a so-called crosspiece, that is a particle profilecompletely filling the intermediate space between the cover layers inthe region of the edge. A commercially available edge of the desiredtype can then be adhesively attached to such a crosspiece. Suchcrosspieces are mechanically very stable. However, they contributesignificantly to the overall weight of the board and can only beretrofitted with considerable effort. They are therefore suitable inparticular for fitting at the time that the lightweight building boardis made, and consequently particularly for industrial production.

On the other hand, so-called support edges are known. These are plasticstrips or plastic laths which are attached to the edge between the coverlayers, the cover layers generally also being milled on the inside. Theactual edge with the decoration is then glued onto this support edge.The document EP 1 640 128 shows as a variant a method in which the edgeis glued onto the support edge before the support edge is attached.

The support edge technique is also quite laborious and necessitates theuse of machines especially provided for the support edges. For anythingother than industrial production, their use entails disadvantages and iseven virtually impossible.

BRIEF SUMMARY OF THE INVENTION

It is consequently an object of the invention to provide a method forproducing a lightweight component and a support element intended forsuch a method that overcome disadvantages of the prior art and, inparticular, are also suitable for non-industrial production.

According to one aspect of the invention, it is proposed to provide thelightweight component having two cover layers, for example of wood or aderived timber material, and a filling arranged in between with an edgesupport comprising a thermoplastic material (generally a plasticcontaining a thermoplastic polymer) after the cutting-to-size operation.This takes place in such a way that said edge support is anchored fromthe narrow side both in the first cover layer and in the second coverlayer, wherein the anchorage is achieved by the edge support beingbrought into contact with the respective cover layer and mechanicalvibrations being coupled into the edge support by a sonotrodeapproaching from the narrow side (that is to say, not through the coverlayers), wherein the edge support at the same time is pressed againstthis cover layer in such a way that, in the region of a transitionbetween the thermoplastic material and the derived timber material ofthe cover layer, part of the thermoplastic material is liquefied andforced into the cover layer material, thereby producing a positivelyengaging anchorage after hardening. This is carried out with oneextended edge support in a continuous process or with a plurality ofedge supports in a repeated process until an extended region of thenarrow side (‘extended’ means, for example, that the ‘horizontal’ extentalong the narrow side is much greater than the thickness of thelightweight component) is provided with the edge support or with theedge supports (and under some circumstances with intermediate spacesbetween them). Furthermore, an edge is fastened to the edge support orto the edge supports in such a way that, in said extended region, theintermediate space between the cover layers is closed toward the narrowside.

According to a further aspect of the invention, a method for fasteningan edge to a lightweight component having two cover layers and a fillingarranged in between is provided, the method comprising the followingmethod steps:

-   -   providing an edge support (3) comprising a thermoplastic        material;    -   anchoring the edge support (3) in both cover layers (1.1, 1.2),        the anchorage taking place by the edge support being brought        into contact with the respective cover layer and energy being        coupled into the edge support, the edge support (3) at the same        time being pressed against this cover layer (1.1, 1.2) in such a        way that, in the region of a transition between the        thermoplastic material and the cover layer, part of the        thermoplastic material is liquefied and forced into the cover        layer, whereby a positively engaging anchorage is obtained after        hardening of the thermoplastic material;    -   carrying out or repeating the anchorage until an extended region        of the narrow side is provided with the edge support (3) or with        a plurality of edge supports (3);    -   fastening an edge (11; 14) to an outer surface of the edge        support in such a way that, in said extended region, the        intermediate space between the cover layers is closed toward the        narrow side.

According to the first aspect, the supplying of energy may take place bya sonotrode, through which vibrations are coupled into the edge support.The vibrations can be coupled into the edge support in such a way thatthey are transmitted through the latter to an interface with the coverlayers and the liquefaction takes place as a result of the frictionbetween the cover layer and the thermoplastic material and/or internalfriction of the thermoplastic material (for example assisted by energydirectors) in the region of the interface with the cover layers. As avariant, the liquefaction may also be brought about in contact with acounter element, which may, for example, engage behind an edge supportin an L-shaped manner and with which the pressure of the sonotrode isopposed. However, the coupling may also take place by the liquefactiontaking place directly in contact with the sonotrode, i.e. the mechanicalvibrations are coupled in with a depth of penetration that under somecircumstances is restricted. Also in these embodiments, the liquefiedthermoplastic material is pressed outward and into structures of thecover layers by the compressive force. In this case, the sonotrode may,for example, engage behind the edge support in an L-shaped manner, sothat the liquefaction takes place on the inside of the edge support withrespect to the lightweight component. A counter element acting from theoutside is used to exert a force counter to the pressing force of thesonotrode.

With regard to the liquefaction in direct contact with the sonotrode ora counter element, attention is also drawn to the document WO 2009/052644, to the content of which reference is expressly made here.

The supplying of energy may alternatively also be brought about in someother way, mechanically, by heating or by radiation coupled in forexample through the edge support, which is absorbed at the roughened orfor some other reason absorbent interface between the edge support andthe cover layer.

Terms concerning the spatial orientation such as “horizontal” or“vertical”, “upper side”, “underside”, etc. are used in the present textto make it easier to read. They relate to the lightweight component whenit has been placed with a flat side on a planar surface, with the coverlayers horizontal. They should not of course be interpreted as meaningthat the method described only works in this orientation. It goeswithout saying that—particularly for relatively small lightweightcomponents—it can also be carried out, for example, with the lightweightcomponent oriented vertically or with the lightweight component held atan angle.

The procedure according to the invention produces the importantadvantage that it allows the use of a relatively low-cost element—theedge support—which can also be used with simple means—that is, forexample, an ultrasonic device with a sonotrode. The ultrasonic devicewith the sonotrode may be a portable device (‘handheld device’) or adevice similar to a fixedly installed drilling machine carried by aframe, with which it is possible to carry out not only the fastening ofthe edge support but also other working steps. The ultrasonic device mayalso be a customary stationary ultrasonic machine, as also known forindustrial applications; the procedure according to the invention isalso suitable for industrial application.

The procedure according to the invention also makes it possible that thefilling in the region of the narrow side does not have to be clearedout—and is preferably used as such. Even if it comprises regions runningbetween the cover layers in the final state, the edge support requireslittle depth, and, given sufficiently flexible filling material, saidmaterial can be readily forced in.

Furthermore, the invention makes it possible that the cover layers donot have to be pretreated—for example by providing channels, grooves,etc.—i.e. the at least one edge support is preferably fastened after thecutting-to-size operation, without method steps that are specificallydesigned for the edge support, although such steps are not ruled out.

The fastening of the edge preferably takes place after the anchorage ofthe edge support(s). Between the anchoring step and the edge-fasteningstep, it is possible, for example, for projecting parts of the edge, andpossibly of the edge support(s), also to be milled off. If the fasteningtakes place after the anchorage of the edge support(s), it is alsopossible in particular for curved or angled-away narrow sides to beedged, without excessive stresses occurring.

However, the edge may also be fastened before the anchorage of the edgesupport; this can already take place during production, i.e. the edgemay be constructed during production in such a way that it comprises theedge support. This also includes edge/edge-support assemblies producedas one piece, i.e. in this embodiment the edge and the edge support(s)may also be an integrated, homogeneous or heterogeneous component. Thecoupling-in of the mechanical oscillations then takes place through theedge; the sonotrode therefore acts on the outside of the edge.

During the anchorage of the edge support, a supporting force that isdirected inward—that is to say toward the other cover layerrespectively—is preferably exerted on the cover layer or the coverlayers. This supporting force prevents the cover layers from comingapart when the supporting edges are introduced; this helps, inter alia,to maintain the thickness tolerances of the lightweight building board.

According to the first aspect of the invention, the sonotrode acts fromthe narrow side, therefore does not act through the cover layers.Nevertheless, the edge support preferably lies substantially between thecover layers after the anchorage, that is to say projects at most alittle, and preferably not at all, beyond the cover layers on the rearside (i.e. a large part of the volume, for example at least ⅔ or atleast 80% of the volume, of the edge support material is preferablylocated between the cover layers after anchorage). It is particularlypreferred for the support edge to be flush on the outside, or even setdeeper, so that, during finishing (for example milling to obtain thenecessary planarity) before the actual edge is applied, only perhapscover layers or a little of the edge support is/are milled off.

Following the anchorage and before the fastening of the edge, amaterial-removing working step may be performed in order to ensure asmooth finish toward the narrow side, it being possible for material ofthe cover layers and/or the edge support(s) to be removed.

Although it is therefore preferred for the edge support to be anchoredin such a way that it is lying between the cover layers and is not lyingagainst the cover layers at the end sides, nevertheless, according topreferred embodiments, the sonotrode will drive the edge support againstthe end sides of the cover layers and between the cover layers, while atthe same time coupling in mechanical oscillations, by a pressing forcein the horizontal direction—i.e. application of force parallel to theplane of the cover layers. The liquefaction of the thermoplasticmaterial in this case takes place at the end sides against the coverlayer or the cover layers and/or by friction on the inner surface of thecover layers.

According to one specific embodiment, the rear support comprises aguiding portion, which already lies between the cover layers when therear support is put in place and before the mechanical oscillations arecoupled in, to be precise in such a way that it is in surface-areacontact with the inside of both cover layers and thereby acts in aguiding manner during further pressing in by the sonotrode. The guidingportion protrudes beyond contact surfaces with the cover layers into theregion between the cover layers (i.e. possibly into the region of thefilling).

In order that the mechanical oscillations can be coupled into the edgesupport, the latter has a corresponding coupling-in surface. In the caseof the embodiments mentioned above, with the pressing force in thehorizontal direction, this coupling-in surface lies on the rear side(that is to say proximally) and is substantially vertical, and forexample approximately parallel to the extent of the narrow side.

According to an alternative embodiment, the pressing force is notexerted horizontally, but vertically by the sonotrode. If that is thecase, the sonotrode has a portion which protrudes into the space betweenthe cover layers during the anchoring process. By contrast with thepreferred situation when anchorage is effected by a horizontal force—theanchorage in the upper and lower cover layers then does not takes placesimultaneously but successively. This embodiment is most particularlypreferred in conjunction with edge supports running in the manner of azigzag or network.

In the case of these embodiments with a vertical pressing force, duringthe anchoring process the coupling-in surface lies in the interior ofthe region between the cover layers, and, for example, liesapproximately horizontally.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described in detail below on the basisof drawings. The drawings are schematic and not to scale. In thedrawings, the same designations refer to the same or analogous elementsand:

FIGS. 1 a-d show a method according to the invention with a firstembodiment of edge supports;

FIG. 2 shows a variant with an endless edge support;

FIGS. 3 a and 3 b show a continuous strip provided with edge supports;

FIG. 4 shows an edge support placed at an angle;

FIGS. 5 a and 5 b show a method according to the invention with afurther embodiment of an edge support;

FIGS. 6 a and 6 b show a method according to the invention with yetanother embodiment of an edge support;

FIG. 7 shows a variant of an edge support with a hybrid structure; and

FIGS. 8 a and 8 b show a method with a further embodiment of edgesupports in another configuration.

DETAILED DESCRIPTION OF THE INVENTION

The cut-to-size lightweight building board that can be seen in FIGS. 1a-1 d comprises—as also in the embodiments described below—an uppercover layer 1.1 and a lower cover layer 1.2. The cover layers areproduced from a derived timber material; for example, they are formed asparticle boards, fiberboards or laminated (plywood) boards. Theinvention is also suitable, however, for the application where the coverlayers are made of other materials, under some circumstances materialsthat are not wood-based, which have sufficient mechanical strength anddimensional stability and comprise structures that are suitable forinterpenetration with liquefied thermoplastic material, for exampleplastic- or metal-based materials, in particular also compositematerials.

The thickness of the cover layers may be chosen according to theapplications. If the cover layers are made of a derived timber material,the thickness may be, in particular, 10 mm or less, for example between2 mm and 8 mm, since for such thicknesses there is specifically a needfor the edge to be supported.

Arranged between the cover layers is a filling 2. This consists of amaterial that is light in comparison with the cover layers, for examplea honeycomb structure made of card or a similar material. Other fillingsforming walls with cavities lying in between are also conceivable, forexample regularly arranged strips (the lightweight component is thensometimes referred to as a “multi-wall sheet”) or tubular structures.Furthermore, the use of Styropor or similar foams as well as, forexample, aluminum honeycombs is also conceivable. Quite generally, theinvention is not dependent on the type of filling and works irrespectiveof the nature of the filling.

FIGS. 1 a, 1 b and 1 d show sectional representations through alightweight component during various method steps (corresponding to asection along the line B-B in FIG. 1 c), and FIG. 1 c shows a plan view(from the direction of the arrow C in FIG. 1 b) of a region of thelightweight component during the method according to the invention.

An edge support 3 of the type depicted in FIG. 1 a consists of athermoplastic material, for example a polymer such as polyamide, apolycarbonate or a polyester carbonate, or else anacrylonitrile-butadiene-styrene (ABS), styrene acrylonitrile, polymethylmethacrylate, polyvinyl chloride, polyethylene, polypropylene andpolystyrene. In addition to the thermoplastic polymer, the material mayalso comprise suitable fillers, for example reinforcing fibers, forexample glass or carbon fibers. Quite generally, all materials with asufficiently high strength, and sufficiently high modulus of elasticityof, for example, at least 0.5 GPa, that can be locally liquefied byultrasound are suitable. These materials are generally the samematerials that are also suitable for ultrasonic welding. To take anexample, ABS is a particularly suitable material.

The edge support 3 has a vertical extent that is a little less than thethickness of the lightweight building board. At the contact surface 3.1with the cover layers 1.1, 1.2, it comprises energy directors, which areformed for example as projecting corners or ridges tapering to an edge.Furthermore, formed in the region between the cover layers 1.1, 1.2 is aprojecting guiding portion 3.2, the vertical extent of which correspondsto the distance between the cover layers 1.1, 1.2. A rear surface 3.3(with respect to the lightweight board in the configuration of FIG. 1 a)is substantially planar and suitable as a coupling-in surface for themechanical oscillations. For the anchorage of the edge support 3 to thenarrow side of the lightweight building board, the edge support ispositioned on the narrow side and pressed against it (arrows 7). Thepressing force is exerted by a sonotrode 5, the coupling-out surface 5.1of which lies flat against the coupling-in surface 3.3. At the sametime, an inwardly directed supporting force (arrows 8) is exerted on thecover layers 1.1, 1.2, and mechanical oscillations 9 are coupled intothe edge support 3 through the sonotrode 5. The guiding portion 3.2thereby ensures that the orientation of the edge support is defined andthat no undesired tilting occurs during the subsequent melting.

The mechanical vibrations are, for example, ultrasonic oscillations. Ingeneral, oscillations in a frequency range between 2 kHz and 100 kHz,preferably between 10 kHz and 40 kHz, for example about 20 kHz, areused; other frequencies are not ruled out. The power of the devicegenerating the oscillations—a commercially available ultrasonic devicemay be used—depends on the dimensionings; it may lie in the rangebetween 100 W and 2 kW.

The pressing force 7 (and possibly the supporting force 8) mayoptionally be exerted already before the mechanical oscillations begin,in order to press the edge support 3 a little into the material of thecover layers already in the region of the contact surface 3.1, which inthe subsequent step makes it even easier for the edge support to beguided and can ensure optimum introduction of the mechanicaloscillations into the edge support. It is particularly favorable if thesupporting force 8 is exerted already before the edge support is placedon, in order to ensure that the cover layers are kept fixed in positionduring the entire process.

As soon as the mechanical oscillations 9 are coupled in, mechanicalenergy is absorbed, in particular in the region of the contactsurfaces—on account of the energy directors and the friction with thematerial of the cover layers—and as a result the liquefying of thethermoplastic material is initiated. The material begins to melt and ispressed into the cover layers 1.1, 1.2. At the same time, incipientmelting of the thermoplastic material may also take place in the regionof the horizontal supporting surfaces 3.4 of the guiding portion, onaccount of the friction with the cover layers.

After the mechanical oscillations end, the liquefied material setsagain, and a stable positively engaging connection with the material ofthe cover layers is obtained. This is represented in FIG. 1 b.

This anchoring process is carried out for a plurality of edge supports 3along the narrow side, the edge supports preferably being arranged atregular intervals, which can be seen particularly well in FIG. 1 c.

In this case, each edge support may be anchored individually, or anumber of edge supports may be inserted simultaneously with the aid ofan extended sonotrode, covering a number of edge supports.

This has the overall effect of producing an extended region of thenarrow side, which is provided with edge supports in such a way that theedge 11 can be adhesively attached to the flat rear side 3.3, serving inthe previous step as a coupling-in surface for the mechanicaloscillations. This is illustrated in FIG. 1 d.

Before the adhesive attachment of the edge, a milling or grinding of thenarrow side—including the edge support—may possibly also take place, inorder that the lightweight component has a smooth, regular surface inthe region of the narrow side.

If an edge support 3 of the type represented in FIG. 1 a is of atransparent configuration, electromagnetic radiation may be coupled intoit instead of or in addition to mechanical vibrations, for example fromthe rear-side surface 3.3 into the region of the contact surfaces 3.1,the latter being configured by roughnesses, pigments or other means insuch a way that the electromagnetic radiation is absorbed there. Theabsorption has the effect that the thermoplastic material in the regionof the interface heats up, and ultimately liquefies, which with thesimultaneous exertion of a pressing force 7 can likewise lead to theanchorage as represented in FIG. 1 b.

FIGS. 1 a to 1 d illustrate the fastening of a plurality of discreteedge supports arranged at regular intervals. Instead, however, acontinuous edge support (“endless edge support”) may also be used. Suchan edge support may, for example, comprise a cross section such as thecross section illustrated in FIG. 1 a of the discrete edge supportsdescribed above. It may be obtained in a continuous process with asonotrode that is advanced in the manner of a roller or with a sonotrodethat is moved over the rear side in the manner of a smoothing iron.However, a continuous edge support may also be fastened portion byportion by an iterative process, which is illustrated in FIG. 2. FIG. 2shows a view analogous to FIG. 1 c with a continuous edge support 3. Theregions 12.1, 12.2, 12.3, 12.4, which are covered by the sonotrodeduring the anchoring, are represented by dashed lines. As depicted, theyare chosen, for example, to be slightly overlapping.

As represented in FIG. 2, the continuous edge support may also comprise,on the rear side, a corresponding decoration and form the edge, inparticular if the edge is in any case constructed as a laminate.

If, as in FIGS. 1 a-1 d, discrete edge supports are anchored, it may beof advantage if the edge supports 3 do not have to be placedindividually but are supplied in a form in which they are fastened atthe ideal intervals on a connecting element, for example a strip. Thisis illustrated in FIGS. 3 a and 3 b. FIG. 3 a shows a front view—i.e. aview from the lightweight component side (arrow A in FIG. 3 b)—of suchan arrangement. FIG. 3 b shows the representation of a section along theline B-B in FIG. 3 a. The edge supports 3 in FIGS. 1 a-1 d of the typedepicted are adhesively attached on the strip 14 or welded onto thestrip. After the anchorage of the edge supports 3, the strip 14 may bepulled off in a process of the type described on the basis of FIG. 1 ato 1 d, or it may also remain where it is, so that its rear side servesas an adhering location for the attachment of the edge 11. As a furtheralternative, the strip may be supplied in a relatively stable form andalready be provided with the desired decoration on the rear side, sothat it serves itself as the edge. If the connecting element does notserve as the edge, it does not have to be configured as a strip, butmay, for example, also be a network, an assembly of a number ofrelatively narrow strips arranged next to one another or some otherflexible connecting means defining the distances between the edgesupports.

The variant of the edge support depicted in FIG. 4 differs from those ofFIGS. 1 a-1 d and 3 a-3 b in that, on account of its outer form and theform of the guiding portion, it is at an angle when it is placed incontact with the lightweight component. This has advantages inparticular whenever, following the anchorage, the narrow side is alsomilled or ground. In the case of a straight arrangement—i.e. if the edgesupport is perpendicular on the flat sides—there is the risk of the edgesupport as a whole being caught by a milling or grinding head and, inthe worst case, torn out. The angled position allows the head to actcontinuously on the edge support.

The angled position of the edge support also makes it possible for theedge to be supported over a greater length.

The variant according to FIG. 4 may optionally—as indicated by thedashed lines—likewise be pre-assembled on a strip.

FIGS. 5 a and 5 b show an embodiment in which, in the anchored state,the contact surfaces 3.1 with the energy directors do not lie againstthe narrow side at the end but lie against the inside of the coverlayers 1.1, 1.2 adjacent to the narrow side. An outer height h₁, i.e.the height measured between the edges or tips of the energy directors,is in this case dimensioned such that it is greater than the distancebetween the cover layers 1.1, 1.2. In other words, when the edge support3 is inserted between the cover layers, the energy directors are againstsaid cover layers, so that, as in the case of the examples describedabove, a horizontal pressing force 7 can be applied along the plane ofthe lightweight component. An inner height h₂, i.e. a height without theenergy directors, may correspond approximately to the distance betweenthe cover layers.

In the embodiment according to FIGS. 5 a and 5 b, the anchorage takesplace primarily on the inside of the cover layers. The embodiment hasthe advantage that the edge support can disappear completely between thecover layers, i.e. pressing force 7 and mechanical oscillations 9 can beapplied until the sonotrode is against the cover layers at the ends. Inthe case where the sonotrode is formed in such a way, the edge supportcan even be recessed just a little.

Even if in the case of the edge support of this embodiment there is noguiding portion projecting beyond the contact surface 3.1, the actualedge support body (i.e. the edge support without the energy directors)can act in a guiding manner during introduction if the inner height h₂is chosen to correspond to the distance between the cover layers. Thisalso applies if the edge support according to FIG. 5 a and FIG. 5 b isformed at an angle by analogy with FIG. 4.

Also in the case of edge supports of this embodiment, a supporting force8 is exerted on both cover layers. The supporting force 8 is especiallyimportant here, since the introduction of the edge support according toFIGS. 5 a and 5 b would have the tendency to push the two cover layersapart if no supporting force were present.

The embodiment according to FIGS. 5 a and 5 b—like that according toFIGS. 1 a-1 d—may also be brought about by the anchorage of individualedge supports, the anchorage of a number of edge supports connected toone another by a strip (or network or the like; a strip may optionallyform the edge) or by the anchorage of a continuous edge support (with orwithout an edge).

It is a preferred principle of the invention that the sonotrode acts onthe edge support from the narrow side—that is to say not through thecover layers. In the embodiments described above, the pressing force 7acts from the end side, that is to say horizontally. An embodiment inwhich the sonotrode likewise acts on the edge support from the narrowside, but in which the pressing force is applied vertically, isdescribed below on the basis of FIGS. 6 a and 6 b.

FIG. 6 a shows a view analogous to FIG. 1 c from the front side; FIG. 6b shows a sectional representation with a sonotrode. As can best be seenin FIG. 6 a, the edge support 3 runs continuously, that is to say as inFIG. 2 as an “endless edge support”. The edge support 3 compriseshorizontal regions 3.5, which respectively lie with the contact surface3.1 against one of the cover layers 1.1 and 1.2, as well as transitionalregions 3.6 connecting these horizontal regions. The horizontal regions3.5 are respectively located alternately on the inside of the uppercover layer 1.1 and of the lower cover layer 1.2.

FIG. 6 b illustrates how the edge support 3 according to FIG. 6 a isanchored in the lightweight component. The sonotrode has the form of a Tor L piece with a laterally protruding portion 5.2, which is insertedinto the intermediate space between the cover layers 1.1, 1.2. The upperside 5.1 a and the underside 5.1 b of this portion form the coupling-outsurfaces for the anchorage of an upper horizontal region 3.5 in theupper cover layer 1.1 and a lower horizontal region 3.5 in the lowercover layer. FIG. 6 b illustrates the situation during the anchorage ofa lower horizontal region 3.5. The pressing force 7 is downwardlydirected. In this embodiment, the supporting force 8 is at the same timethe counter force opposing the pressing force. In the case of theanchorage on the underside, it can be applied simply by the lightweightcomponent resting on a horizontal underlying surface. In the case of theanchorage of the upper horizontal regions—with an upwardly directedpressing force—the counter force—then acting on the upper cover layer1.1—is advantageously actively applied.

During the anchorage of the edge support 3, for example, upper and lowerregions are anchored alternately along the narrow side. However, it isalso possible, for example, first to anchor all the upper regions andthen to anchor all the lower regions. Optionally, this may beaccompanied by turning the lightweight component as a whole around. Inthe latter case, active application of the counter force may be madesuperfluous, in that during the anchoring there is always downwardpressing and the supporting force can always be applied by theunderlying surface against which the pressing force is directed.

The attachment of the edge with the decoration takes place by analogywith the above embodiments; here, too, a milling or grinding of thenarrow side may take place in advance. This embodiment is evenparticularly suitable for this, since, as illustrated, the edge supportcan be anchored such that it is set back with respect to the end side ofthe cover layers. If it is done in this way, it is necessary for thecover layers to be removed until they are flush with the edge support,in order for adhesive attachment of the edge to become possible.

As a difference from the embodiments described above, however, in thecase of the example according to FIGS. 6 a and 6 b, of course, thecoupling-in surface does not serve as the rear-side surface forfastening the edge, but the outer surface.

Many other embodiments besides are conceivable, for example withnetwork- or grid-like edge supports, differently formed sonotrodes, etc.It is also possible to construct the edge support from a number ofmaterials and not just from one material, as in the examples illustratedabove. FIG. 7 shows an edge support 3, which comprises, at least in theregion of the contact surface 3.1, a thermoplastic part 3.11 and anon-thermoplastic part 3.12, for example of a building materialcontaining wood. If such a part 3.12 is attached on the rear side, thatmay be particularly advantageous, for example, for the adhesive bondingwith the edge.

Depicted in FIGS. 8 a and 8 b is an arrangement in which the sonotrode 5acts on the inside of the edge support 3 and exerts the pressing force 7from the inside. FIG. 8 a shows a sectional representation analogous toFIGS. 1 a, 1 b, 1 d, 5 a and 6 b; FIG. 8 b shows a section along theline B-B in FIG. 8 a. The mechanical vibrations 9 are coupled into thesonotrode 5, which engages behind the edge support in an L-shapedmanner. A counter element 15 is used to apply the necessary counterforce 7′. The liquefaction takes place here in the region of theinterface between the sonotrode 5 and the edge support 3, it beingpossible for the edge support to comprise energy directors 3.8, wherebythe liquefaction reliably takes place directly at the interface onaccount of the vibrations coupled into the edge support. As indicated inFIG. 8 a, on account of the pressing force, the liquefied thermoplasticmaterial is displaced upward and downward and forced into structures ofthe cover layers, which brings about the anchorage. Even if thepenetration of the cover layers with thermoplastic material willgenerally not be as intensive as when the edge support itself is pressedagainst the cover layer and liquefied in contact with it, even with thisprocedure sufficient anchorage can nevertheless be obtained.

In an arrangement that is virtually identical to FIGS. 8 a and 8 b, themechanical vibrations can also be coupled into the edge support 3 fromthe outside, the liquefaction taking place in contact with the counterelement. In such an arrangement, the roles of the sonotrode and of thecounter element are changed over in FIGS. 8 a and 8 b, i.e. 15 thenrefers to the sonotrode and 5 refers to the counter element. Thevibrations 9 are then coupled into the sonotrode 15; 7′ refers to thepressing force and 7 refers to the counter force.

The method according to FIG. 8 a and 8 b or the variant thereof can alsobe carried out by energy other than mechanical energy, for example heat,being coupled into the edge support. Instead of a sonotrode, a heatingelement is then used as the tool.

What is claimed is:
 1. A continuous edge structure being an edge or edgesupport for a lightweight building element, wherein: the lightweightbuilding element is a planar structure two cover regions and a fillingregion between the cover regions; the edge structure comprises contactsurfaces with a thermoplastic material shaped to lie against the coverregions in an outer surface of the lightweight building element andfurther comprises, opposite the contact surfaces, a coupling-in surfacefor coupling energy into the edge structure; the edge structure isshaped so that at least a portion of the thermoplastic material isliquefied and pressed into the cover regions when energy is coupled intothe edge structure while the contact surfaces are pressed against thecover regions; the edge structure comprises at least regions which areformed to run between the cover regions after the pressing thethermoplastic material portions into the cover regions; and, the edgestructure is continuously extended to run along an edge of thelightweight building element.
 2. The edge structure according to claim 1being a laminate of an edge with a decoration and an edge support oredge support elements comprising the thermoplastic material.
 3. The edgestructure according to claim 1 being free of elements protrudingvertically beyond the cover regions.
 4. The edge structure according toclaim 1 further comprising energy directors at the contact surfaces. 5.The edge structure according to claim 1, wherein the contact surfaceswith the thermoplastic material extend continuously along the edge. 6.The edge structure according to claim 1, comprising a strip extendedcontinuously along the edge and comprising the coupling-in surface, theedge structure further comprising a plurality of edge support elementsattached to the strip.
 7. The edge structure according to claim 6,wherein the strip has a decoration on a rear side.
 8. The edge structureaccording to claim 7, wherein the rear side comprises the coupling-insurface.
 9. A method of fastening an edge to a lightweight buildingelement, the method comprising the steps of: providing the lightweightbuilding element, being a planar structure with two cover regions and afilling region between the cover regions; providing a continuouslyextended edge structure, the edge structure comprising contact surfaceswith a thermoplastic material shaped to lie against the cover regions inan outer surface of the lightweight building element, and, opposite thecontact surfaces, a coupling-in surface for coupling energy into theedge structure; coupling energy into the edge structure and pressing thecontact surfaces against the cover regions until at least a portion ofthe thermoplastic material is liquefied and pressed into the coverregions; and repeating or continuing the steps of coupling and pressinguntil the edge structure is attached to the lightweight building elementat a plurality of discrete locations or over an extended region along anedge of the lightweight building element.
 10. The method according toclaim 9, wherein the step of coupling energy into the edge structurecomprises coupling mechanical vibration into the edge structure.
 11. Themethod according to claim 9 wherein continuing the steps of coupling andpressing comprises moving along the edge a roller capable of couplingenergy into the edge structure through the coupling-in surface.
 12. Themethod according to claim 9, wherein continuing the steps of couplingand pressing comprises moving along the edge a flat tool capable ofcoupling energy into the edge structure through the coupling-in surface.13. The method according to claim 9, wherein repeating the steps ofcoupling and pressing comprises repeatedly pressing a tool capable ofcoupling energy into the edge structure through the coupling-in surfaceagainst regions of the edge.
 14. The method according to claim 13,wherein the regions of the edge are overlapping.
 15. The methodaccording to claim 9, wherein the edge structure is an edge support, andwherein the method comprises the further step of attaching an edge tothe edge support.
 16. The method according to claim 15, wherein the stepof attaching is carried out after the step of repeating or continuing.17. The method according to claim 9, wherein the edge structurecomprises the edge.